Mucosal Hyperplasia and Antifungal Efficacy of Modified Versus Conventional Soft Denture Liners: A Systematic Review and Meta-Analysis

Abstract

Background: Soft denture lining materials are frequently colonised by Candida albicans, contributing to denture stomatitis and, in chronically affected patients, inflammatory papillary hyperplasia of the denture-bearing mucosa. Incorporation of antifungal or antimicrobial agents into soft liners has been proposed as a strategy to reduce fungal colonisation and improve mucosal health relative to conventional, unmodified liners.

Objectives: This systematic review aimed to evaluate the antifungal efficacy of modified versus conventional soft denture liners against Candida albicans, and to characterise the available evidence on mucosal response, including inflammatory papillary hyperplasia and denture stomatitis severity, and on liner mechanical properties associated with antimicrobial modification.

Methods: A targeted literature search identified in vitro and clinical studies comparing antimicrobial-modified soft denture liners with unmodified controls. Twenty-two unique records were identified and screened; twelve studies met inclusion criteria and were assessed in full text, with all twelve confirmed eligible and included in narrative synthesis. Quantitative synthesis was performed descriptively where studies reported directly comparable antifungal-efficacy data; formal statistical meta-analysis was not performed, given substantial heterogeneity in modifying agent, liner base material, and outcome metric across the included literature.

Results: Twelve studies were included: eleven in vitro (bench) studies and one randomised clinical trial. Modifying agents included silver nanoparticles, chitosan, plant-derived compounds (garlic, neem, tea tree oil), and synthetic pharmacological agents (nystatin, chlorhexidine, ketoconazole, miconazole, itraconazole). Silver nanoparticle-modified silicone liners demonstrated concentration-dependent antifungal efficacy ranging from 16.3% to 52.5%. Plant-derived and chitosan-based modifications consistently inhibited C. albicans growth in vitro. Chlorhexidine diacetate produced a dose-related antifungal effect and measurable drug release, whereas chlorhexidine hydrochloride showed no inhibitory effect, indicating that antifungal efficacy is salt-form dependent for at least one agent. Mechanical property data from a cluster of related in vitro studies indicated that most antifungal agents at minimum inhibitory concentration preserved liner hardness and tensile strength, with the exception of miconazole and itraconazole, which reduced tensile strength and, for miconazole, increased hardness at 14 days. In the single identified clinical trial, nystatin- and chlorhexidine-modified liners achieved complete absence of mycelial Candida on palatal cytological smears by day 14, compared with persistence of mycelial forms in patients receiving an unmodified liner. No included study reported inflammatory papillary hyperplasia as a graded clinical outcome.

Conclusions: Antimicrobial modification of soft denture liners consistently reduces Candida albicans colonisation relative to conventional liners across the available in vitro and limited clinical evidence, with agent- and concentration-dependent effects on liner mechanical integrity. The evidence base for mucosal hyperplasia specifically remains critically underdeveloped, and well-designed clinical trials using standardised hyperplasia grading are needed before firm clinical recommendations can be made regarding this specific outcome.